Safety device



I Aug- 19; 1952 A. J. RlTcHxE 2,607,510'

.SAFETY DEVICEl Filed Feb. 8. 1946 NvENjroR CLL'FWMJQJHA v BY @mm..Q/(Jwmm.

- ATTORNEYS Patented Aug. 19, 1952 Alexander .L Ritchie, Bayonne, J.,assigner to Electric Boat Company, Bayonne, 1. a corporationof NewJersey Application February 8, 1946, Serial No. 646,295

7 Claims. 1 Y Thisl invention relates to safety devices, fluid relief ordischarge devices, and the like, and especially to devices of thischaracter responsive to the occurrence of a predetermined conditionWithin a closed container or responsive to other contemplated conditionsor circumstances, The invention aims to provide an improved safety orother device of this character.

Safety devices are customarily provided in a wide variety of' industrialvoperations for protection against excessive pressures, temperatures orother dangerous conditions, and devices ofthe same general character maybe used for they relief or discharge of iiuids (either gaseous orliquid) under desired conditions or at desired times. Typical examplesof such operations are medium and high pressure steam generators,chemical processes handling fluidsy and especially liquids underconditions of high` pressure, high temperature, or both, equipment forhandlingv corrosive liquors, various equipments for dischargingA specietypes of gases or liquids at will or at contemplated intervals or undercontemplated conditionssuch. as synthetic. smoke generators, and

apparatus for discharging vpoison gas, insecticides,

etc. The most common safety devices now used are frangible discs and popor relief valves. These devices are rarely used singly, tWo at leastbeing usually provided in order to safeguard the equipment against thefrequent failure of the device to operate as contemplated. Among themany causes for the failure of frangible discs to so operate may hementioned non-uniformity in the discs themselves, changingcharacteristics due to aging or the like, corrosion of the disc etc. Popvalves require constant maintenance, since they tend to stick, the valveseats are easily corroded leading to erratic operation,- and theoperating characteristics of `the customary springs change due to aging,corrosion or the like.

One of the aims of the present invention is to provide an improvedsafety device of simple construction and positive action adapted for usein arresting high temperatures, high pressures or other dangerous orcontemplated conditions in a wide variety of containers or vesselscontaining fluids and especially liquids of any sort. device, in one ofits aspects, comprises a disc adapted to close a relief or dischargeopening in one wall of the container and operatively connected with astud or anchor secured to the container proximate the Wall opening. Anexpansible means, preferably of the explosive type such as a squib, isassociated With the disc for rupturing its operative connection'withvthe stud to The thereby permit the escape of fluid through the Wallopening. The rupturing action of the expansible means is appropriatelyinitiated vby the occurrence of some predetermined condition Within thecontainer, or by other suitable means. In another aspect of theinvention, the disc is inwardly deflected by the tightness of itsoperative connection to the stud so that the amount of the deflection isa measure of the closing or sealing effectiveness of thel disc 'withrespect to the Wail opening. Increasing pressure within the containerreduces the deflection and a predetermined excessive pressure overcomesthe deflection Y, entirely and fluid escapesy from the container untilthe excessive pressure Within the container is remedied and the discresumes, to some degree at least, its deflected contour.

The foregoing and other novel features of the invention will ce bestunderstood from' the following description, taken in conjunction withthe accompanying drawing, in Which Fig. 1 is a sectional view ofthedevice of the invention (functioning as a safety device) in its presentpreferred form,

Fig. 2V is a transverse' section on thefsectien line 2--2 of Fig. 1,

Figs. 3, l and 5 are enlarged explanatory details of portions of Fig. l,f

Figs. 6 and 7 illustrate a modied type of sealing means, and

Fig. 8 illustrates a modification of one feature of the device.

Fig. 1 of the drawing illustrates the invention in the form of a safetydevice operatively connected to a container il! of Which only a portionof one Wall is shown. The container may be of any type or form such as asteam boiler, a vessel for carrying out chemical processes or forholding fluids and especially liquids of a corrosive nature, a storagecontainer for liquids, such as synthetic smoke compositions and thelike, to be discharged at Will or under contemplated conditions etc. Inmost instances, the container is subjected to conditions that give riseto high pressures, or high temperatures, or both, therein, and thesafetyA device is provided to relieve excessive or dangerous conditionsof temperature, pressure, or both. The container has an opening rIl inone Wall thereof, which may be thetop or side wall. Where only a gas isto be discharged from the container through the opening H, the openingWill usually be near or on the top of the container, and Where some orall of the liquid contents of the container is to'. be discharged, the

' opening will be beneath the liquid level in the container, or adepending outlet or induction pipe or tube I2 may be connected to theopening as indicated in Fig. 8.

A connecting ring I3 of approximately the same diameter as the opening II and registering therewith is welded or otherwise appropriately securedto the outside of the container. The connecting ring I3 is internallythreaded and a throat-ring I and integral Stud or stud I is threadedtherein. The threaded connection between the rings i3 and I4, and henceof the throat-ring I4 to the container, is hermetic to prevent theescape of iluid therethrough, and if desired this may be assured by theprovision of appropriate packing I3 or other suitable sealing expedient.The stud I5 is positioned within the container in the axis of theopening II andV is integrally connected to the throat-ring I4 by apyramidal spider I6, the stud being located at the vertex of the spider.Various other constructions are suitable for operatively securing thestud to the container proximate the opening I I and for securing thethroatring to the container, and the throat-ring and stud need not beintegral, but may be separate parts. Where the outlet pipe I2 ispresent, the stud may advantageously be welded to that pipe as indicatedin Fig. 8, in which case the spider IE is unnecessary.

The stud I5 has a threaded axial bore or socket in which the shank of ablow-tube I'I is screwthreaded. The blow-tube has a hollow body for theaccommodation of expansible, and preferably explosive, means I8, such asa squib. A blowdisc I9 is threaded into the end of the hollow body ofthe blow-tube I1, and has on its inner face a circular ridge 2B adaptedto form a gastight seal with an annular seat 2| of relatively soft metal(e. g. Babbitt or other anti-friction bearing metal) inlaid in the outerend face of the throat-ring I4. The outer end face of the throat-ring I4has an integral guide ring 22 extending outwardly beyond the seat 2l toassist in centrally positioning the blow-disc I9 as it is screwed (by aspanner or the like) into the blowtube I'I, inside diameter of the guidering being slightly greater than the peripheral diameter of the disc.

A bell-shaped coupling or transformation piece 23 is screw-threaded onthe throat-ring I4 and has a circular ridge 24 adapted to form agastight seal with an outer annular seat 25 of relatively soft metalinlaid in the outer end face of the ring I4 surrounding and concentricwith the inner seat 2|. The coupling 23 is firmly held in its sealingposition by a lock bolt 26 adapted to bite into a circumferential seatof relatively soft metal 21 inlaid in the outer cylindrical surface ofthe ring I4 intermediate its ends. The circular ridges 20 and 24 haveslightly rounded apexes which bite into 'the soft metal seats with aflow of the soft metal around the apex to form a perfect seal, asillustrated in Figs. 4 and 5.

The squib I8 is axially threaded into a central hole in the disc I9. Thesquib may advantageously be a copper tube lled with an explosivecompound preferably slow-burning, such for example, as coarse grainsingle base nitro-cellulose powder. An electric match, or other suitableprimer, is appropriately associated with the explosive compound and itscontrol cable 28 is arranged within the coupling 23 and has a terminalsocket 29 screw-threaded in the wall of the coupling. The cable 28 iselectrically connected to a contact instrument 30 by a cable 3I having aterminal plug 32 adapted to be inserted in 4 the socket 29. Atemperature or pressure responsive device 33 is appropriately positionedwithin the container I0 and is operatively connected to the instrument30 and the latter is connected to a suitable source of electric energy3d.

In the operation of the device, the parts hereinbefore mentioned areassembled as described. Assuming that it is desired to protect thecontainer against excessive pressure, the means 33 will be responsive tochanges in pressure within the container. The instrument 30 is set sothat upon the occurrence of a predetermined excessive pressure withinthe container the cable SI will be electrically connected to the sourceof electric energy 34 and the explosive in the squib I8 will be set oiby the electric match or other primer associated therewith. Theresulting explosion ruptures the screw-threaded connection between theblow-tube I'I and the disc I9, and the gaseous pressure within thecontainer forces the disc away from its closing position with respect tothe opening I I and against the interior lugs of the coupling 23. Thelugs serve to arrest the movement of the disc and provide a stop againstwhich the disc is rmly held by the pressure of the discharging fiuid.The free cross-sectional area of the larger part of the coupling 23 issubstantially greater than the area of the disc I9, to provide adequatespace for the flow of the discharging uid around the disc while heldagainst the lugs 35. Where it is necessary or desirable to convey thedischarging uid to a storage tank or other disposal means, a dischargepipe 36 is connected to the end of the coupling 23 by a nut 31. Theouter end face of the coupling has an iniaid annular seat 38 of softmetal with which a circular ridge 39 of the inner end of the dischargepipe cooperates to form a gas-tight seal, in the manner hereinbeforedescribed.

The rupturing of the operative connection between the blow-tube and theyblow-disc by the action of the explosive means is such that these partscan be used only vonce and they must be replaced by new parts when thedevice is again reassembled. These parts, as well as the stud andthroat-ring, may advantageously be made of brass, and the cost ofreplacing the expandable parts is insignificant. The container isusually made of steel or steel alloys such for example as stainlesssteel.

The means 33 may be responsive to temperature changes within thecontainer, and in that case the safety device of the invention will comeinto operation upon the occurrence of a predetermined excessivetemperature within the container. Instead of being automaticallycontrolled by a pressure or temperature responsive device positionedWithin the container, the rupturing action of the explosive means may bemanually controlled in response to a visible or audible danger signal.In other instances the contents of the container Ill, coniined under asuitable gaseous pressure, may be discharged at will or as contemplatedby manual or automatic actuation of the instrument 30. A

The blow-disc I9 additionally serves as a safety valve. When the disc isscrewed into the blowtube I1, its circular ridge 20 bites into the'seat2 I. The resistance to this biting action progressively increases as thedisc is screwed in and the metal of the seat flows around the ridge 20,and ultimately becomes so great that further turningof the disc causesYits outer surface to deec tin- The disc isA screwed in until apredetermined A deflection or concavity has been thus attained. -Anyincrease in the pressure within the container I0 will decrease thisdeflection or concavity of the discs outer surface, and should thepressure increase sufficiently to entirely overcome the deflection, theseal between the ridge and the seat 2I is broken or opened to permit arelease of the pressure within the container until the deflection of thedisc is sufficiently restored to renew the seal. This safety valveaction of the disc is automatic and only comes into action wheneverapredetermined excessive or critical pressure exists within thecontainer. When the pressure is relieved below the critical point,thedisc automatically resumes its sealing position. The amount ofdeflection or concavity of the disc, with the normal pressure within thecontainer, is a measure of the excessive pressure required to open orbreak the seal between the ridge 20 and the-seat 2|. The curvature ofthe rounded apex of the ridge 20 (as well as the similar ridges of thedevice) is correlated to the hardness of the metal of the seat 2 I. Inow prefer to make these seats of an alloy containing about 11%antimony, 2% arsenic and the balance lead. With seats of such an alloy,the radius of curvature of the apex of the ridge may advantageously be@le inch. With seats of harder metal, the radius of curvature will besmaller and with seats of softer metal, the radius of curvature Will begreater.

Where it is undesirable to make use of the safety valve action of thedisc I9, it will be so tightly screwed into the blow-tube I'I that itsdeflection will not be overcome by any pressure within the containerbelow that at which the rupturing action of the squib I8 is initiated bythe pressure responsive means l33. On the other hand, the safety valveaction of the disc I9 may be advantageously used in conjunction with therupturing of the operative connection between the disc and blow-tube.Thus, the deflection of the disc I9 maybe such that it relievesperiodically-occurring excessive pressures of short duration without therelief or discharge of any substantial amount of fluid from thecontainer. The pressure responsive means 33 may then be suitablydampened or time-lagged so that the predetermined excessive pressurewill not cause the instrument to initiate the action of the explosivemeans I8 unless and until that condition of excessive pressure persistsfor a definite time interval. If the condition of excessive pressuredoes continue for that time interval, the disc I9 will be blown aw'ayfrom its closing position with respect to the opening I I. The advantageof this dual action of the safety device of the invention is thatdangerous pressure conditions of short duration are automaticallyalleviated without interrupting the operation being carried on in thecontainer It or discharging its contents. How'- ever, if the dangerouscondition persists then full safety relief is afforded.

In Figs. 6 and '7 of the drawing, I have shown a modified form ofsealing means particularly adapted to be used under conditions of hightemperature. In lieu of the circular ridge 24 of the coupling 23, thecoupling 23 of Fig. 6 has an annular recess 49, and the outer face ofthe throat-ring I4 has an oppositely positioned annular recess 4I. Ametal sealing ring 42 is positioned between the recesses 40 and 4 I.When the coupling 23 is screwed onto the throat-ring I4', the metal ofthe sealing ring 42 iiows into and substantially fills the recesses dand 4I and also extrudes to some extent into the space between theopposing faces of the coupling and throatvterminates in a circularflange II and the throatring I4 is welded or otherwise-appropriatelysecured to the inside of theflange. The delivery end of the vtube I2 iswelded or otherwise appropriately secured to the innerend of thethroatring I4'. The threaded shank of the blow-tube I1 is screwedintothe socket of the studi I5 and in other respects the construction isthe same as thatofFig.1. f j v The device of the invention is of` simpleconstruction, positive in its action and can be constructed at low cost.There are no mechanical parts to get out of order, and no parts whoseaction is impaired or whose working characteristics change with aging.The action of the explosive means in removing the-closure of the reliefopening Il is sureand positive, and the rupturing action of theexplosive means is'readily initiated by a wide variety o f standardrecording or indicating instruments now on the market, and in particularinstruments responsive to temperature or pressure. Thus, the action ofthe device is nctdependent upon some part positioned in situ `whosecharacteristics are variable and whose positiveness of operation isuncertain. The relief action of the device of the invention is initiatedby remote control, and the action is therefore not subject todeleterious influences in the immediate vicinity of the device itself.

1. A safety device comprising the combination with a container having anopening-in one wall thereof, of a stud securedto `the container in theaxis of said opening, a blow-tube having a screw-threaded connectionwith said stud, a disc having a screw-threaded connection with saidblow-tube andclosing said opening, explosive means within saidvblow-tube for rupturing the screw-threaded connection between theblowtube and disc and therebypermit the disc to move away from itsclosing position with respect to said opening, and means responsive tothe occurrence of a predetermined condition withinthe container forinitiating the-rupturing action of said explosive means. .y

2. A safety'device comprising the combination with a container having anopening in one wall thereof, of a stud positioned within the-containerand secured thereto proximate said opening, a throat-ring registeringwith said opening and hermetically secured to said .container and havingan annular seat of relatively soft` metal on its outer face, a discconnected to said stud and having a circular ridge on one face forming asealing contact with said annular seat to close said opening, explosivemeans positioned between said stud and disc for rupturing the connectiontherebetween and the sealing contact of said circular ridge and saidannular seat, and means responsive to the occurrence of a predeterminedcondition within the container for initiating the rupturing action ofsaid explosive means.

3. A safety device comprising the combination with a container having anopening in one wall thereof, of a stud positioned within the containerand secured thereto proximate said opening, a throat-ring registeringA,with said opening and hermetically secured to said container andhaving Han annular seat of .relatively soft metal on its outerfface, ablow-tube connected to said stud, a'disc'connecte'd to said blow-tubeand having a circular ridge on one face forming a sealing contact withsaid'annular seat'to close said opening, explosive means within saidblowtube forrupturing the connection of the'disc therewith and thesealing contact of said circular ridge and said annular seat, and meansre- 'sponsive'to `the occurrence of a predetermined condition within thecontainer for initiating the rupturing action o f said explosive means.

4. A safety device comprising the combination with acontainer containinga uid under pressure and having anopening in one wall thereof, of a studpositioned within the container and secured thereto proximate saidopening, a throatring registering with said opening and hermeticallysecured to the container and having two concentric annular seats ofrelatively soft metal on its outer face, a coupling connected to saidring and having an interior circular ridge forming a seal with the outerof said annular seats, a disc positioned Within said coupling andconnected to said stud and closing said opening by forming a seal withthe inner of said annular seats, explosive means positioned between saiddisc and said stud for rupturing the connection of the disc with saidstud to permit the fluid pressure within the container to move the discaway from its sealing position with the inner of said annular seats, andmeans responsive to the occurrence of a predetermined condition withinthe container for initiating the rupturing action of said explosivemeans.

5. A safety device comprising the combination with a containercontaining a fluid under pres-` sure and having an opening in one wallthereof, of a stud secured to the container proximate said opening, ablow-tube secured to said stud and extending through said opening, athroatring registering with said opening and hermetically secured to thecontainer, a disc connected to said blow-tube and through the tightnessof that connection forming a sealing contact of variable eiectivenesswith said throatring to close said opening, said disc being capable ofinward deection when with a normal pressure within the container itsconnection to the blow-tube is suiciently tightened and of returning toits original contour to permit the escape of fluid through the sealingcontact whenever a predetermined excessive pressure exists within thecontainer, explosive means within said blow-tube for rupturing theconnection between the tube and disc and thereby permitting the escapeof fluid from said container through said opening, and means forinitiating the rup-turing action of said explosive means.

6. A device of the character described comprising the combination with acontainer having an opening in one wall thereof, of a stud positionedwithin the container and secured thereto proximate said opening, ablow-tube secured to said stud and extending through said opening, athroat-ring registering with said opening and hermetically secured tosaid container and having an annular seat of relatively soft metal onits outer face, a disc connected to said blowtube and having a circularridge on one face forming a sealing contact with said annular seat andto close said opening, explosive means within said'blow-tube forrupturing the connection between the tube and disc, and means forinitiating the rupturing action of said explosive means.

7.'A device of the character described comprising the combination with acontainer containing a fluid under pressure and having an opening in onewall thereof, of a stud secured to the container proximate said opening,a blowtube secured to said stud and extending through said opening, athroat-ring registering with said opening and hermetically secured tosaid container and having an annular seat of relatively soft metal onits outer face, a disc connected to said blow-tube and having a circularridge on one face forming a sealing contact of variable effectivenesswith said annular seat to close said opening, said disc being capable ofinward deflection when with a normal pressure within the container itsconnection to the blow-tube is sufciently tightened and of returning toits original contour to permit the escape of fluid through the sealingcontact whenever a predetermined excessive pressure exists within thecontainer, explosive means within said blow-tube for rupturing theconnection between the tube and disc, and means for initiating therupturing action of said explosive means.

ALEXANDER J. RITCHIE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name l Date 1,761,932 Nutt June 3, 19301,970,718 Tryon et al. Aug. 21, 1934 1,984,510 Allen et al. Dec. 18,1934 2,194,442 Grant, Jr. Mar. 19, 1940 2,304,417 Mason Dec. 8, 19422,351,526 Lebus June 13, 1944 2,406,502 Lines Aug. 27, 1946 2,408,774Goddard et al. Oct. 8, 1946 2,436,364 McDowell Feb. 17, 1948 2,480,967Ritchie Sept. 6, 1949

